Stock velocity measurement device



p 1968 J. F. SCHMAENG STOCK VELOCITY MEASUREMENT DEVICE 4 Sheets-Sheet l Filed Dec. 8, 1965 INVENTOR. i @222 Faizfiza'ezgg m 1 BY @w W WAQATTORNEl S Sept. 3, 1968 Filed Dec. 8, 1965 J. F. SCHMAENG 3,399,565

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Sept. 3, 1968 I INVENTOR. @1222 Fcfzmezg (WM k ATTORNEYS w w V m I United States Patent 3,399,565 STOCK VELOCITY MEASUREMENT DEVICE John F. Schmaeng, Rockton, Ill., assignor to Beloit Corporation, Beloit, Wis., a corporation of Wisconsin Filed Dec. 8, 1965, Ser. No. 512,399 4 Claims. (Cl. 73-194) ABSTRACT OF THE DISCLOSURE Apparatus for determining the velocity of stock as it flows from the slice opening in the head box of a papermaking machine. The apparatus includes an impact tube movable into the flow of stock at the slice opening and from which issues a jet of fluid against the flow of fluid against the flow of stock. The fluid which issues from the impact tube is maintained at a constant velocity. An indicator is provided to indicate the static pressure of the fluid in the impact tube, the static pressure varying as a function of variations in the velocity of the stock flowing from the slice opening.

This invention relates generally to papermaking apparatus and more particularly to improvements for ascertaining the velocity of the stock as it flows out of the slice opening of a head box of a papermaking machine onto a traveling forming surface.

Many papermaking machines comprise a head box onto which a stock slurry is delivered and a traveling forming surface which receives a stream of the stock from the slice opening of the head box and upon which the paper web is initially formed.

It is generally considered desirable for the formation of quality web that the velocity of the stock as it flows from the head box and is delivered to the forming surface be correlated with the velocity of the forming surface. While it is possible to provide a degree of correlation merely by a visual observation of the relative velocities, this may be quite unreliable and a more consistently accurate means of measurement is indicated.

The speed of the forming surface, whether it be a Fourdrinier wire, the peripheral surface of a cylinder, or the like, is not difficult to ascertain. Measuring the velocity of the stock, however, presents a different and more difficult problem.

The present invention provides a means for determining the stock velocity through the utilization of a variable electrical resistance mechanism connected into an electric circuit across which is applied a fixed E.M.F. The electrical resistance mechanism comprises a coil of high resistance wire exposed to the interior of a core formed in a non-conductive housing. A reservoir filled with mercury is formed in the housing at the base of the core.

The reservoir is in fluid communication with a selected point in a fluid-carrying conduit which has mounted at one end thereof a small pitot tube, which is referred to hereinafter as an impact tube. The outlet of the impact tube is arranged to eject a small jet of fluid into the stock stream, preferably in a direction substantially opposite to the direction in which the stock is flowing.

The conduit at the other end thereof is connected to a source of pressurized fluid.. The fluid may preferably be water, although it will become manifest herein that other pressurized fluids are also suitable. The static pressure of the fluid in the conduit at the point thereof which is in communication with the mercury reservoir will vary inproportion to the velocity of the stock flowing across the outlet of the impact tube. As the static pressure increases a portion of the mercury in-the reservoir rises in the core, thereby shunting out a portion of the Patented Sept. 3, 1968 coil of wire and causing an increase in the flow of current through the circuit. As the static pressure decreases the level of mercury in the core falls, thereby having the effect of decreasing the current flow in the circuit. An ammeter can be connected in the circuit for reading such variations in current, and the current reading, of course, can be calibrated to directly reflect velocity of the stock.

The variations in the current flowing in the circuit can also be utilized through suitable apparatus to regulate the slice opening of the head box, the flow rate of the stock supply pump, etc., whereby to maintain a predetermined velocity of the stock at the slice opening.

The impact tube is swingably mounted such that it can be periodically pivoted into the stock stream for measurement of the stock velocity, and pivoted out of the stock stream when not in use. Shower means and associated apparatus are also provided for cleaning the impact tube when it is positioned out of the stock stream.

It is, therefore, an object of the present invention to provide improved means for measuring the velocity of stock at the slice opening of a head box of a papermaking machine.

Another object of the invention is to provide means for measuring stock velocity with minimal physical disturbance of the flow of the stock.

A further object of the invention is to measure stock velocity as a function of its effect on the pressure of another fluid being injected into the stock.

Still another object of the invention is to measure stock velocity by means of a variable electrical resistance mechanism connected into an electrical circuit having a fixed voltage applied thereacross and means for varying the effective resistance of the mechanism and therefore the current flowing through the circuit as a function of the stock velocity.

Yet another object of the invention is to provide a pressure responsive, mercury column, variable resistance mechanism comprising a coil of high resistance wire exposed to the interior of a core and fluid mercury riseable within the core a distance proportionate to the value of a pressure applied to the mercury for shunting out a proportionate portion of the coil to vary the resistance thereof as a function of the pressure applied to the mercury.

Another object of the invention is to provide a papermaking machine having a head box for supplying a stream of stock to a traveling forming surface with improved means for measuring the velocity of the stock being applied to the forming surface, such means comprising a conduit connected to a source of pressurized fluid and having an impact tube mounted thereon for directing a jet of the fluid into the stream of stock, means in communication with the conduit at a selected point thereof and responsive to the pressure of the fluid at said selected point for providing a signal which varies in accordance with variations in the fluid pressure at said selected point, means for moving the impact tube selectively into and out of the stock stream and means for cleaning the impact tube.

Many other features, advantages and additional objects of the present invention will become manifest to those versed in the art upon making reference to the detailed description which follows and the accompanying sheets of drawings, in which preferred structural embodiments incorporating the principles of the present invention are shown by way of illustrative example only.

On the drawings:

FIGURE 1 is a fragmentary vertical sectional view of a head box of a papermaking machine having mounted thereon a stock flow measurement device constructed in accordance with the principles of the present invention;

FIGURE 2 is a wiring diagram showing the electrical circuitry of the present invention;

FIGURE 3 is a plumbing diagram showing the hydraulic circuitry of the present invention;

FIGURE 4 is a front elevational view of a variable electrical resistance mechanism constructed in accordance with the principles of the present invention;

FIGURE 5 is a vertical sectional view of the mechanism of FIGURE 4 taken substantially along lines V--V tional view taken along lines XIXI of FIGURE 10.

Although the principles of the present invention are of utility in measuring the characteristics of any fluid a particularly useful application is made to the measurement of stock velocity in a papermaking machine which, in an illustrative embodiment thereof shown herein in FIGURE 1, comprises a head box having formed therein a tank 16, which head box receives stock slurry from a suitable source and discharges or deposits the stock on a traveling Web forming surface as, for example, a Fourdrinier wire.

A front portion 17 of the head box 16 comprises an apron 18, which constitutes a forward projection of the bottom wall of the head box, and a downwardly and forwardly sloping wall 19 which, in conjunction with the apron 18, forms a tapered passageway 20 for conveying the stock from the tank portion of the head box 15 to a slice opening 21 formed between vertically spaced distal ends 22 and 23 of the apron 18 and the wall 19. The stock flows from the slice opening 21 to a traveling web forming wire situated below the slice opening.

In the manufacture of quality web it is generally considered desirable to correlate the speed of the web forming surface with the velocity of the stock as it is deposited on the forming surface. In the illustrated embodiment of the head box 15 the velocity of the stock as it emerges from the slice opening 21 can be varied through the provision of means for varying the area of the slice Opening 21. Thus a forward end portion 24 of the wall 19 is hinged as at 26 to the remaining portion of the wall and an adjustment rod 27 is mounted on the end portion 24. Movement of the rod 27 can be controlled by any suitable means which may be of the manual or automatic type. It will be appreciated that correlation of the velocities of the stock emerging fromthe slice opening and of the forming wire .by means of varying the area of the slice opening 21 has its practical limitations since there are, of course, generally preferred maximum and minimum velocities of the stock at the slice opening 21. In addition the thickness of the web formed on the wire is a function of the area of the slice opening and the desired thickness of the web may therefore also enter into limitations placed upon the adjustment of the slice opening. The speed of the forming wire is, of course, adjustable.

In correlating the velocities of the stock and forming wire visual observation can be quite inaccurate and therefore quite unsatisfactory. It is desirable to provide means for determining with a relatively high degree of accuracy the respective velocities of the forming wire and of the stock leaving the slice opening. As noted, the speed of the forming wire can be determined through the utilization of any number of suitable and well known means. In determining the velocity of the stock, however, the following considerations render this a dilferent and a more difficult problem.

First of all, the stock should not be unduly agitated as it emerges from the slice opening in the interest of a quality web. This considerationplaces a limitation on-the physical size of any measurement member situated directly in the stock stream.

Further, any measurement member situated within the stock stream should be designed to prevent flocculations and agglomerations of the fibers of the stock.

In accordance with the principles of this invention means are provided for accurately measuring the velocity of the stock without the formation of substantial and quality-reducing flocculations and agglomerations. The invention comprises the utilization of a relatively small Pitot tube 28 having a lower neck portion 29 open at a distal end 30 thereof for discharging a relatively small jet of fluid into the stock stream at the slice opening 21 of the head box 15. The tube 28 may be more descriptively referred to as an impact tube since it is the force or impact of the stock acting upon the jet of fluid being emitted from the tube 28, and the effect upon the pressure of the fluid being discharged from the tube 28 as a result of the velocity of the stock, which results indirectly in a measurement of the velocity of the stock.

The impact tube 28 is mounted on the front portion 17 of the head box 15 for movement of the neck 29 thereof selectively into and out of the path or stream of the stock. Accordingly the conduit or tube 28 is mounted at a central portion 31 thereof on a generally inverted U-shaped arm 32 which, in turn, is pivotally mounted on a stationary shaft 33. The pin 33 is fixedly mounted on a flange 34 connected in fixed assembly to an elbow bracket 36. A lower end 37 of the bracket 36 is secured to the wall 19 of the head box 15.

Since it is not necessary to continuously measure the velocity of the stock, the impact tube 28 need only periodically be lowered or dipped into the stock stream. From the lower or operating position of the impact tube as indicated in the full lines in FIGURE 1, the tube may be pivoted or raised to a second or inoperative position thereof indicated by the dashed lines in FIGURE 1.

When the tube 28 is raised to its inoperative position it is desirable to clean the tube, and particularly the neck portion 29 and outlet 30 thereof, to prevent stock build-up thereon. For this purpose an impact tube shower is indicated at reference numeral 38 as being disposed above the impact tube 28 in its inoperative position. The shower 38 is connected by means of a conduit 39 to a suitable source of water and to provide a spraying effect a pair of spray nozzles 40 and 41 may be mounted on the shower 38.

In order to collect the spray water, a shower pan 42 houses the impact tube at the inoperative position thereof. The collected spray water is removed from the shower pan 42 by means of a drain line 43 which is open at a lower end 44 thereof. A vacuum or siphon effect is applied to the drain line 43 in order to draw the collected spray water from the shower pan 42.

The pan 42 is formed at one end of an arm 46 which is also pivotally mounted on the flange 34 by means of another stationary pin or shaft 47. In order to pivot the arm 46 about the shaft 47 a pressurized fluid cylinder 48 is provided having one end 49 thereof pivotally mounted on a bracket 50 which extends from the elbow bracket 36 and having an opposite end 51 thereof, which is actually the distal end of a telescopic arm 52 of the cylinder, pivotally connected to the arm 46 on a side of the shaft 47 opposite the side at which the part 42 is formed.

Thus the shower pan 42 can be moved from a raised position thereof as indicated by the dashed lines to a lowered position thereof as indicated by the solid lines in FIGURE 1. The arm 32 which mounts the impact tube 28 is also connected to the shower pan 42 by means of a linkage 53 which is pivotally connected at one end 54 thereof to the arm 32 and at an opposite end'56 thereof to the shower pan 42. As a result of this linkage, as the pressure cylinder 48 is operated to pivot the shower pan v 42 to the'raised position thereof'the impacttube 28 is also raised thereby to 'its inoperative or raised position. By operating the cylinder 48 in an opposite direction, the impact tube 28 is lowered to its operative position and the shower pan 42 is also lowered so as to avoid interference with the tube 28. v

In order to prevent overtravel of the tube 28 one end 57 of the arm 32 is provided with a threadedly adjustable bolt 58 which abuts the peripheral surface of a collar 59 of the elbow bracket 36 when the tube 28 reaches its operating position. V

In the hydraulic circuit shown in FIGURE 3 the impact tube 28 is disclosed as being connected to a conduit 60 through a flexible conduit 61 in order to accommodate the pivotal movement of the impact tube. The conduit 60 is, in turn, connected to a suitable source of pressurized fluid as, for example, a pressurized water pipe 60a.

. As noted, it is the effect on the pressureof the fluid in the conduit 60 and the impact tube 28 rise result of the force of the stock acting on the jet of fluid being discharged from the impact tube 28 into the stock stream which afiords a variable for measuring the velocity of the stock. In accordance with the invention this variable serves to vary a signal which in turn provides a means for measurement. Accordingly, a variable electrical resistance mechanism indicated generally at reference numeral 62 is connected into the conduit 60. Generally, the mechanism 62 comprises a resistor element 63 connected at opposite ends to wiring 64 and 66 shown in the wiring diagram of FIGURE 2 to provide a circuit across which is applied a voltage provided by suitable means as indicated diagrammatically at 67.

The conduit 60 is tapped as at 68 for fluid communicatiori with' a reservoir 69 filled with fluid mercury. The mercury can rise in a column or core 70 into engagement with the resistor element 63 whereby that portion ofthe resistor 63 which is engaged with the column of mercury 70 is effectively shunted out. The greater the water pressure at tap- 68 the higher will rise the column of mercury 70 and the greater will be that portion of the resis'tor 63 shunted out. A decrease in water pressure at tap 68 conversely has the effect of reducing the pressure in reservoir 69 lowering the level of the mercury column 70 and decreasing the shunted out portion of the resistor63. I

The electric power source67 is adapted to apply a fixed E.M.F. to the circuitry 64, 66. A voltmeter 71 may be applied-across the power source 67 to indicate this fixed i As the "shunted out portion'ofthe resistor element 63 increases and decreases as a result of pressure variations of the water in conduit 60 the current in the electric circuit decreases andincreases accordingly as indicated by an ammeter 72 connected in the circuit. A manually adjustable rheo stat 73 is also provided in the circuit to establish manually a maximum current flow through the circuit. t

It will be appreciated that in order to provide a linear relationship between the static pressure of the water in conduit 60 and the flow of current through the electric circuitry 64, 66 without thenecessity of an electrically compensating mechanism the velocity of the water through conduit 60 must be maintained at a fixed level regardless of the velocity of the stock and the effect thereof on the jet of water being discharged from the impact tube 28. In order to provide a fixed flow rate of the water through conduit 60 a flow meter 74 is mounted in conduit 60,

ahead of which is mounted a water pressure compensator 76. The flow meter 74 may 'beof the fixed orifice type and the compensator- 76 automatically adjusts the flow rate through conduit 60 so as to maintain a fixed pressure drop, for example, about 3 pounds per square inch, across the flow meter 74. A filter 77 and a water shut-off valve 78 are also mounted in the conduit 60 ahead of the pressure compensator 76.

I If desired, water can be supplied to the impact tube shower 38 from the same water line 62 which supplies the water to the impact tube 28. Thus, the conduit 39 is connected to the water line 62 and in order to facilitate the operation of the shower a solenoid operated valve 79 is connected in conduit 39 along with a shut-off water valve 80.

In many papermaking machines of the Fourdrinier type water is also supplied to the wire pit. In FIGURE 3 another conduit 81 is shown connected to water pipe 82 and leading to the wire pit of the papermaking machine. Conduit 81 can be utilized in draining the impact tube shower pan 42 when the impact tube 28 is in its inopera tive position and being cleaned, and for that purpose an eductor venturi 82 is mounted in the conduit 81 and is also connected to the drain line 43 which extends into the impact tube shower pan 42. Again, a shutoff valve 83 may be mounted in the conduit 81 for obvious purposes.

Referring to FIGURES 4 and 5, the variable electrical resistance mechanism 62 is more particularly characterized as comprisinga housing 84 which includes a vertically upright back member 86, a vertical front member 87, a horizontal front member 88 and a reservoir member 89. Members 87, 88 and 89 have vertically aligned back walls 90, 91 and 92, respectively, which are separated from a vertical wall 93 of member 86 by means of a spacer bar 94.

The vertical front member 87 has formed therein an inlet 96 and an outlet 97 interconnected by means of a bore 98. The inlet 96 and the outlet 97 are connected to the conduit 60 (FIGURE 1) whereby the water flowing through conduit 16 to the impact tube 28 passes through the bore 98.

A reduced diameter vertical bore 99 is also formed in the vertical front member 87 adjacent the bore 98 and in parallel relation thereto. Bore 99 is connected in fluid communication to the bore 98 through a horizontal branch passageway 100 formed at the upper end of bore 99. A lower end 101 of the smaller bore 99 opens into a reservoir 102 formed in member 89. The reservoir 102 is filled with fluid mercury in the operative condition of the mechanism 62 to provide a shunt for the resistor element 63.

The front wall 93 of the vertical back member 86 has formed therein a thin, elongated vertical groove or recess 103 which is in communication with the reservoir 102 at a lower end 104 thereof through an aperture 106 formed in the spacer plate or bar 94 and a passageway 107 formed in the reservoir member 89. Thus, as the static pressure of the water in conduit 60 increases to increase the pressure in bore 99 (which is filled with water), the pressure on the mercury in reservoir 102. increases to urge a quantity of the mercury upwardly in the groove or core 103 formed in the vertical back member 86. An upper end 108 of the core 103 is vented to atmosphere through a branch passageway 109.

Referring to FIGURES 2 and 3 in conjunction with FIGURES 8 and 9, it will be noted that the resistor element 63 comprises a helical coil of wire which is Wound vertically upwardly along the groove or core 103. In the embodiment of the element 63 shown in FIGURES 8 and 9, the windings as indicated at 110 are embedded almost entirely within the back member 86 except for an arcuate portion 111 thereof which is exposed to the interior of the core 103. The back member 86 may be formed of any non-conductive material, such as plexiglass, and in the embodiment illustrated members 86-89 and 94 of the mechanism 62 are all formed of this material.

Opposite ends 112 and 113- extend through the back member 86 and are connected, respectively, to wires 64 and 66 (FIGURE 2).

The resistor element 63 may be preferably wound of relatively high resistance wire such as Nichrome. Fluid mercury, used in the illustrated embodiment for shunting out portions of the resistor 63, has an electrical resistance somewhat similar to Nichrome but the cross-sectional area of the fluid mercury in the core 103 is so much greater than the cross-sectional area of the windings of the resistor 63 that the overall resistance afforded by the fluid mercury is substantially less than that of the Nichrome wire. In the illustrated embodiment the wire has about lOO windings per inch with an overall resistance of about 80-0 ohms.

In the embodiment illustrated in FIGURES 10 and 11 the windings of the resistor 63 are disposed completely within the core 103. In this embodiment the diameter of the core 103 may be greater than the diameter of the core in the embodiment shown in FIGURE 8 in order to accommodate additional fluid mercury to lessen the electrical resistance thereof.

In order to provide a zero adjustment of the variable electrical resistance mechanism 62 and the ammeter 72 means are provided for selectively adjustably controlling the level of mercury in the core 103 for any given water pressure. As shown in FIGURES 46, a mercury level regulator indicated generally at reference numeral 114 comprises a threaded stud 116 mounted in the horizontal front member 88 and having an enlarged head portion 117 formed at an inner end thereof and disposed in a recess 118 situated above and opening downwardly into the reservoir 102. A knurled outer end 119 facilitates adjustment of the stud 116, and as the stud is threaded into the member 88 the enlarged head portion 117, which is conically shaped in the illustrated embodiment, moves downwardly toward the reservoir 102 to raise the level of the mercury in the core 103. Conversely, threading the stud 116 outwardly has the effect of raising the enlarged head 117 to lower the level of the mercury in core 103.

The mercury level may also be regulated by adjusting the upright back member 86 and the spacer 94 vertically with respect to members 87, 88 and 89. For this purpose members 86 and 94 are connected in fixed assembly to members 87-89 by means of a plurality of threaded bolts as at 119 housed in oversized bores 120 formed in members 86 and 94. In order to accommodate such movement, an inner vertical leg 121 is formed in the passageway 107 of the reservoir member 89 and is surrounded by a sealing member such as an O-ring at 122. As the upright back member 86 and the spacer 94 are adjusted vertically the level of mercury in the core 103 varies accordingly for any given pressure of the water.

A plurality of cross bars 123 interconnect opposite pairs of the bolts 119 in order to rigidity the assembly of the mechanism 62. In order to fill the reservoir 102 with mercury a bore 124 is formed in the reservoir member 89 adjacent a bore 126 which houses the stud 116, and a threaded filler plug 127 closes off the bore 124 after the reservoir 102 has been filled with mercury. It should be understood that it is not essential to the principles of the invention that the fluid discharged from the impact tube 28 be water. Other liquids as well as air and inert gases can also be utilized as a substitute for the water.

Although minor modifications might be suggested by those versed in the art, it should be understood that I wish to embody within the scope of the patent warranted hereon all such modifications as reasonably come within the scope of my contribution to the art.

I claim as my invention: 1. In a papermaking machine having a head box and a slice opening in the head box for supplying a stream of stock from the slice opening to a traveling forming surface, means for providing a measurement relating to the velocity of the stock at the slice opening comprising, conduit means having means for connection to a source of pressurized fluid,

an outlet in said conduit means situated at said slice opening for directing a jet of the fluid from said conduit means into the stream of stock,

regulator means in said conduit means for maintaining a constant velocity 'of said pressurized fluid at said outlet regardless of variations in the velocity of the stream of stock, and means associated with said conduit means and responsive to variations in the pressure of the fluid in said conduit means at a selected point therein for providing a signal which varies as a function of variations in the pressure of the fluid at said selected point,

the pressure of the fluid at said selected point varying. as a function of variations in the velocity of the stock at said slice opening, and said signal providing means comprising an electric circuit, means for applying a given E.M.F. across said circuit, and resistance means in said circuit responsive to variations in the pressure of the fluid at said selected point for varying the electrical resistance of said circuit as a function of variations in the pressure of the fluid at said selected point. 2. The papermaking machine as defined in claim 1 wherein said resistance means comprises a resistor element connected in said circuit, electrically conductive means movable with respect to said resistor element for shunting out portions of said element, and means responsive to variations in the pressure of the fluid at said selected point for moving said electrically conductive means with respect to said resistor element as a function of the pressure of the fluid at said selected point,

whereby the current of said circuit varies as a function of the pressure of the fluid at said selected point. 3. In a papermaking machine having a head box and a slice opening in the head box for supplying a stream of stock from the slice opening to a traveling forming surface, means for providing a measurement relating to the velocity of the stock at the slice opening comprising, conduit means having means for connection to a source of pressurized fluid, an outlet in said conduit means situated at said slice opening for directing a jet of the fluid from said conduit means into the stream of stock, means associated with said conduit means and responsive to variations in the pressure of the fluid in said conduit means at a selected point therein for providing a signal which varies as a function of variations in the pressure of the fluid at said selected point,

the pressure of the fluid at said selected point varying as a function of variations in the velocity of the stock at said slice opening, said conduit means comprising an impact tube, means for pivotally mounting said impact tube for selective movement thereof between first and second positions at which the impact tube is disposed within and without the stream stock at the slice opening of the head box, respectively, impact tube shower means for spraying cleaning water on the impact tube when the tube is pivoted to said second position thereof, an impact tube shower pan associated with said impact tube in said second position thereof for collecting the cleaning water sprayed on the impact tube, and a drain pipe in said shower pan for removing the collected cleaning water from the pan. 4. Apparatus for providing a signal which varies as a function of variations in the pressure of a stream of fluid comprising,

a housing having a vertically extending core and a reservoir at the base of the core, a quantity of fluidmercury within the reservoir risable 9 10 within the core upon an increase in pressure in said 1,468,854 9/1923 Bacharach 73-401 reservoir, 2,018,431 10/'1935 Wolf 73-205 means communicating the stream of fluid with sa1d 2 379 746 7/1945 Poitier 137 499 reservoir for simultaneous change in pressure thereof, u a helical coil of high resistance wire the windings of 5 2,901,040 8/1959 Gade 162-259 which are disposed principally outside of said core 2, 57 11/1959 Cook 73205 with only portions of each of the windings being 2,979,130 4/1961 Smith 162263 X gf g g 2 d 3,102,422 9/1963 'Hatfield 73 194 means or app ying a e across s 1 cor an means for measuring the current in said coil. 10 3312106 4/1967 73 203 X 3,337,393 8/1967 Parker 162263 References Cited C. Prlmary Examzner.

1,393,942 10/1921 Chadwell 73401 X E. D. GILHOOLY, Assistant Examiner.

1,449,437 3/1923 Obermaier 73-398 XR 15 

